Abstract: This report presents the results of finite element (FE) analytical studies, using monotonic pushover analysis, to investigate the behavior of unstiffened thin steel plate shear walls (SPSW) with openings on the infill plate. Two infill plate options, the perforated and the cutout corner SPSW, are investigated. First, a series of individual perforated strips were analyzed to develop a fundamental understanding of the behavior of a complete perforated SPSW. After generating a large number of data points and using fine mesh models, "smooth" curves of total uniform strip elongation versus perforation ration were obtained. Finite element models of complete perforated SPSW were developed to verify the individual strip model results and to evaluate the effects of different infill thicknesses, perforation diameters, and material idealizations. Two finite element models of cutout corner SPSW were then developed to study the effect of a relatively thick fish plate installed perpendicularly to the flat-plate reinforcement. The effects were examined in terms of global effects, such as frame deformation and shear strength of the systems, as well as local effects adjacent to the cutout corners, such as local buckling, stress distribution, and forces applied by the cutout edge reinforcement to the beam and columns. Recommendations and considerations are proposed to help design perforated and cutout corner SPSW.